Pathways to Production Using Solar Heat Unlocking Solar Thermochemical Potential: Receivers, Reactors, and Heat Exchangers SETO webinar-workshop December 3, 2020

PRESENTED BY Anthony McDaniel([email protected])

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525. 1 SAND2020-13487 PE This presentation does not contain any proprietary, confidential, or otherwise restricted information Thermochemical is a Simple Concept: 2 Heat + H2O In, H2 + O2 Out

R. Perret, SAND Report (SAND2011-3622), Sandia National Laboratories, 2011. G. J. Kolb, R. B. Diver, SAND Report (SAND2008-1900), Sandia National Laboratories, 2008. S. Abanades, P. Charvin, G. Flamant, P. Neveu, Energy. 31, 2805–2822 (2006).

Direct storage of in a reduced metal . Hundreds of cycles proposed. ➢Multi-phase, multi-step, thermochemical-electrochemical hybrids

Multinational R&D efforts have gravitated towards two-step, non-volatile MOx 3 STC H2 Materials Theme: Exchange and Transport

Challenge: decrease TR and increase OX Oxygen storage materials with a twist.

➢O-atom “harvested” from H2O not air ➢Bulk phenomena largely govern O-atom exchange with environment ➢Understanding thermodynamics, kinetics, transport, gas-solid interactions, solid-solid interactions is important

Material subject to extreme environments. ➢ cycling on the order of seconds ➢Large thermal stress per cycle o o o • 800 C< T <1500 C; ∆TRATE ~100 C/sec ➢Large chemical stress per cycle -14 -1 • 10 atm< pO2 <10 atm

Water splitting at extremely low pO2. ➢Strongly reducing “oxidizing” atmosphere -13 “O” activity in H2O:H2 gas > solid gas <10 atm

Receiver/Reactor and Material R&D must not evolve in “isolation”

J. E. Miller, A. H. McDaniel, M. D. Allendorf, Advanced Energy Materials. 4, 1300469 (2014). A Brief History of Non-Stoichiometric STC Water Splitting Materials

Cycle thermodynamics: tradeoff between , TTR, and H2O:H2

spinel perovskite Fe2+/Fe3+ (unsupported) systems: TM2+/TM3+/TM4+ (Mn, Fe, Co) systems: High redox capacity (>0.1) High redox capacity (>0.1)

Moderate TR <1400 C Low-to-moderate TR <1400 C

WS-UNTESTED in H2O:H2 atm WS-PROMISING in H2O:H2 atm

fluorite Ce3+/Ce4+ systems: Low redox capacity (<0.08)

High TR >1500 C

WS-“BEST IN CLASS” in H2O:H2 atm

o WS inactive at TO2,onset <850 C o High H2O:H2 ratio at TO2,onset <1200 C

A.H. McDaniel, Current Opinion in Green and Sustainable Chemistry, 2017, 4, 37–43.

5 A Brief History of Reactor Design Concepts ~100 kg kg CeO ~100

CPR2 2

Different reactor designs have been explored. ➢Fixed material bed, moving material bed, inert gas sweep, vacuum, temperature swing, pressure swing Increasing solar-to-hydrogen efficiency largely drives R&D.

MOx WS cycle has been demonstrated at scales from watts to kilowatts 6 Sandia’s Receiver/Reactor Design Philosophy R. B. Diver et al., J. Solar Energy Engineering. 130, 041001(1)–041001(8) (2008). J. E. Miller et al., SAND2012‐5658 (2012) I. Ermanoski, International Journal of Hydrogen Energy. 39, 13114–13117 (2014). A. Singh et al., Solar Energy. 157, 365–376 (2017) High solar-to-hydrogen conversion efficiency. CR5 ➢Continuous on-sun operation ➢Direct solar absorption ➢Temperature and product separation

➢Heat recovery between TTR and TWS Moving particle bed design advantages: ➢Small reactive particles (100m) not monoliths ➢Only particles are thermally cycled ➢Independent component optimization ➢Reaction kinetics decoupled from reactor mechanics Cascading pressure design advantages: ➢Ultra-low reduction pressure by chamber isolation ➢Decreased pump work requirement CPR2

5 2 CO2 (CR ) and H2O (CPR ) splitting demonstrated at power levels 5-10kWth 7 Desired Material Behavior Defined by Process Economics

Commercial viability key driver when competing against steam reforming and fossil

Redox capacity (MOx/H2). ➢Oxide heating and material inventory Redox kinetics. ➢Cycle time and material inventory PROPERTY IDEAL Earth abundance. ➢Raw materials Redox Capacity HIGH <10:1 (MOx/H2) Redox Kinetics FAST ~sec (match flux) Reduction temperature (TTR). 1 6 ➢Heliostats (solar concentration) Earth Abundance MOD >10 /10 Si

➢Reactor construction materials TTR @ Reduction LOW <1400C H O/H @ Oxidation LOW <10:1 (H O:H ) Steam requirement (H2O/H2). 2 2 2 2 ➢Steam heating and water use Durability HIGH >10 years Durability. ➢Material replacement

J. E. Miller, A. H. McDaniel, M. D. Allendorf, Advanced Energy Materials. 4, 1300469 (2014). I. Ermanoski, J. E. Miller, M. D. Allendorf, Physical Chemistry Chemical Physics. 16, 8418 (2014). Navigating A Highly Constrained Space: Thermodynamic Tradeoffs 8 Affect Process Efficiency and Economics

Receiver/Reactor engineering and material challenges must be addressed simultaneously

I. Ermanoski, N.P. Siegel, E.B. Stechel, J. Solar Energy Engineering, 2013, 135, 031002 A.H. McDaniel, Current Opinion in Green and Sustainable Chemistry, 2017, 4, 37–43 D. R. Barcellos et al., Energy & Environmental Science (2018) doi:10.1039/C8EE01989D 9 Opportunities for Material Discovery

Ideal material is not unobtainium. ➢Desired thermodynamic properties sandwiched between known compounds

Non-stoichiometric oxide community needed to bring expertise into this field. ➢Ideas needed for entropy and enthalpy engineering Continued development and application of DFT. ➢Descriptors beyond vacancy formation energy Advanced experimental methods. ➢High throughput synthesis and characterization ➢Electrochemical approaches ➢Operando X-ray spectroscopies 10 What will it Take for Solar Thermal Technologies to Deliver...

Renewable H2 or solar fuels in general

➢R&D to discover and advance functional materials ➢R&D to discover and advance alternative cycle chemistry ➢R&D to develop solar reactors and synergistic system concepts • extremely high temperatures • high efficiency heat recuperation • hermetically sealed • CSP integration ➢R&D to develop efficient collectors for high concentration and high temperature Large scale demonstrations ➢public—private partnerships New policies and regulation to incentivize and drive private investment 11 Global Initiatives Gaining Momentum Article in March 2018 issue of Chemical Engineering (www.chemengonline.com) titled “Solar Chemistry Heats Up” written by staff editor Gerald Ondrey https://hydrogeneurope.eu/ project/hydrosol-plant

http://english.cas.cn/newsroom/ archive/news_archive/nu2018/201 A 1,000-tonne industrialization of liquid 807/t20180709_194849.shtml solar synthesis project has been launched in Lanzhou, capital city of northwest China's Gansu Province.

https://www.sun-to-liquid.eu/ 12 Acknowledgements

Sandia Labs: Collaborators: ➢Andrea Ambrosini ➢Christian Sattler (DLR) ➢Eric Coker ➢Martin Roeb (DLR) ➢Josh Sugar ➢Nathan Siegel (Bucknell) ➢Ryan O’Hayre (CSM) ➢Michael Sanders (CSM) ➢Jianhua Tong (Clemson) ➢William Chueh (Stanford) ➢Ellen Stechel (ASU) ➢Ivan Ermanoski (ASU) ➢Jim Miller (ASU) ➢Chris Wolverton (NWU)

Work supported by the U.S. Department of Energy Hydrogen and Technologies Office 13 Nature’s Thermochemical Water Splitting Process

Thank you for your attention. Questions?

Source: iStock

Our challenge is to develop efficient and scalable solar-powered reactors producing 100,000 kg H2/day without melting houses